Fluid Turbine Having Improved Cam and Follower Mechanism

ABSTRACT

A fluid turbine comprising a blade pitch control mechanism comprising a cam and at least one rocker assembly, each rocker assembly comprising a rocker arm operable to pivot about an axis of rotation, the blade pitch control mechanism being operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.

SUMMARY OF THE INVENTION

According to a first embodiment, the present disclosure relates to a fluid turbine comprising a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle. A blade pitch control mechanism comprises a cam and at least one rocker assembly, each rocker assembly comprising a rocker arm operable to pivot about an axis of rotation, the blade pitch control mechanism being operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.

According to a second embodiment, the present disclosure relates to a fluid turbine comprising a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle. A blade pitch control mechanism comprising a cam and at least one rocker assembly, each rocker assembly comprising a rocker arm operable to pivot about an axis of rotation and a cam follower bearing, secured to the distal end thereof, operable to ride on a surface of the cam, the blade pitch control mechanism being operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.

According to a third embodiment, the present disclosure relates to a fluid turbine comprising a frame, a rotor, comprising a hub secured to the frame in such manner as to rotate about an axis of rotation with respect thereto and at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle. A blade pitch control mechanism comprises a mostly stationary cam secured to the frame and having a surface defining a rotor blade pitch profile and at least one rocker assembly, each rocker assembly comprising a rocker arm secured to the hub in such manner as to pivot about an axis of rotation with respect thereto and a cam follower bearing, secured to the distal end thereof, operable to ride on a surface of the cam, the blade pitch control mechanism being operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a fluid turbine according to certain embodiments of the present disclosure;

FIG. 2 is an end view of a fluid turbine according to certain embodiments of the present disclosure;

FIG. 3 is an isometric view of a rotor hub according to one embodiment of the present invention;

FIG. 4 is a top view of a rocker assembly according to certain embodiments of the present invention;

FIG. 5 is a front view of a rocker assembly according to certain embodiments of the present invention;

FIG. 6 is an end view of a rotor hub assembly according to certain embodiments of the present invention;

FIG. 7 is a three-dimensional view of a rocker arm assembly according to certain embodiments of the present invention;

FIG. 8 is a section view of the rocker arm assembly of FIG. 7;

FIG. 9 is a three-dimensional view of a rocker arm according to certain embodiments of the present invention;

FIG. 10 is a three-dimensional view of a yoke according to certain embodiments of the present invention; and

FIG. 11 is a three-dimensional view of a blade pitch control link according to certain embodiments of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A system and method of the present patent application will now be described with reference to various examples of how the embodiments can best be made and used. Like reference numerals are used throughout the description and several views of the drawings to indicate like or corresponding parts, wherein the various elements are not necessarily drawn to scale.

FIG. 1 is an isometric view of a fluid turbine 100 according to certain embodiments of the present disclosure. Structurally, turbine 100 consists of a rotor assembly comprising a torque tube 104 riding on bearings 106 mounted on a frame 102. Torque tube 104 is designed to prevent each rotor hub 108 from rotating independently of the other rotor hubs 108. Torque tube 104 is oriented along a central axis which is intended to be disposed generally perpendicular to the direction of fluid flow. The turbine 100 comprises arrays of radially-disposed struts 110 mounted to rotor hubs 108 at their proximal ends and to a set of rotor blades 112 at their distal ends. The rotor blades 112 shown in FIG. 1 are high aspect ratio airfoils/hydrofoils having a clearly defined leading and trailing edge. Turbine 100 shown in in FIG. 1 comprises 10 blades, but alternate embodiments may have more or fewer blades, depending on the application. The rotor blades 112 are attached to the struts 110 in such a manner as to allow the rotor blades 112 to be individually pivoted with respect to the axis of rotation of turbine 100, thus altering the pitch angle of each rotor blade 112 with respect to the direction of fluid flow through turbine 100. The angle of the rotor blades may be controlled via mechanical linkages, hydraulics, pneumatics, linear or rotary electromechanical actuators, or any combination thereof. In certain embodiments, the rotor pitch angle profile may be controlled by a cam-and-follower mechanism operating in concert with one or more of the above systems of actuation, as set forth in further detail below.

FIG. 2 is an end view of a fluid turbine 100 according to certain embodiments of the present disclosure. The fluid turbine 100 shown in FIG. 2 incorporates ten rotor blades 112. The pitch angle of the ten rotor blades 112 are designated angles A-J with the blade pitch angle of the rotor blade at angular position 0 being designated angle “A”. The blade pitch angles of the other rotor blades 112 are designated angles “B” through “J”, at multiples of 36 degrees from angle “A”, counter-clockwise. Thus, angle “B” is the pitch angle of a rotor blade 112 disposed at an angular position 36 degrees counter-clockwise from 0, angle “C” is the pitch angle of a rotor blade 112 disposed at an angular position 72 degrees from 0, and so forth.

Because of the fact that the angle between a rotor blade 112 and the fluid flow will vary as the rotor blade 112 moves around the axis of rotation of the turbine 100, the optimal pitch angle for torque generation will vary accordingly as that rotor blade 112 moves around the axis of rotation. In order to optimize the angle between the blade pitch and the fluid flow, the turbine 100 disclosed herein incorporates at least one mechanism to vary the blade pitch according to angular position as a rotor blade 112 moves around the rotational axis of the turbine 100. The pattern or profile of blade pitch vs. angular position may vary depending on a number of factors, including but not limited to rotor velocity and free stream fluid velocity. Thus, it may be desirable to modify the blade pitch profile as conditions change.

FIG. 3 is an isometric view of a rotor hub according to one embodiment of the present invention. Hub 200 revolves about a cam 204 as the rotor revolves about its axis of rotation. Cam 204 remains stationary inside hub 200 as the rotor revolves. A set of rocker assemblies 206, secured to hub 200, ride on a surface of cam 204 as the hub 200 revolves. Each rocker assembly 206 is connected to an actuation rod 208 and at least one spring 210 secured to a strut at one end and the actuation rod 208 at the other. The springs 210 hold the cam followers securely against a surface of the cam 204.

Each actuation rod 208 is secured to a rocker assembly 206 at its proximal end and to a rotor blade at its distal end. Each actuation rod 208 controls the pitch of a particular rotor blade according to the position of a particular rocker assembly 206, which is, in turn, controlled by the profile of a surface of the cam 204 at the point of contact between the cam 204 and the cam follower of the rocker assembly 206. Thus, a rotor blade at a given radial location will be articulated to a given pitch. As a rotor blade moves about the axis of rotation of the rotor, it will be articulated according to the pattern of the cam, which may be one of the patterns set forth heretofore, or may be a different pattern.

FIG. 4 is a top view of a rocker assembly according to certain embodiments of the present invention. FIG. 5 is a front view of a rocker assembly 206 according to certain embodiments of the present invention. Rocker assembly 206 comprises a rocker cartridge 250 which acts as a frame for rocker assembly 206. Rocker cartridge 250 has a cylindrical body protruding from the back of a front flange, and a generally-cylindrical aperture passing from front to back. A rocker arm 252 is mounted to a shaft passing through the cylindrical aperture in the body of the rocker cartridge 250, and mounted in such a manner as to pivot about an axis of rotation passing through the aperture. In general, rocker arm 252 will pivot on bearings of some type, which may be sleeve bearings, ball bearings or needle bearings, as examples.

A cam follower bearing 254 is secured to the distal end of the rocker arm 252 and oriented in such manner as to freely rotate about an axis of rotation generally parallel to, but offset from, the axis of rotation of the rocker arm 252. Cam follower bearing 254 is designed to ride on the outer surface of cam 204 as hub 200 revolves around stub axle 202. Cam follower bearing 254 may be selected from any one of a number of bearing types, including sleeve bearings, ball bearings or needle bearings, as examples.

As cam follower bearing 254 rides along a surface of cam 204, rocker arm 252 will pivot to follow the profile of a surface of the cam 204, thereby rotating the shaft portion passing through the aperture in the body of the rocker cartridge 250. A lever arm 256 is secured to the shaft portion in such a manner as to pivot with the rocker arm 252. The lever arm 256 is also secured to an actuation rod 208 in such a manner as to move the actuation rod 208 as the rocker arm 252 rotates. With this arrangement, the actuation rod 208 moves according to the profile of the surface of cam 204 as the rocker assembly 206 moves about the cam 206.

FIGS. 6-11 depict a second embodiment of a cam-and-follower mechanism according to certain embodiments of the present invention. FIG. 6 depicts an end view of a rotor hub having an array of ten rocker assemblies 300 disposed circumferentially therein. As seen in FIGS. 7 and 8, each rocker assembly 300 comprises a rocker arm 302 rotatably secured at a center pivot to a yoke 306. The rocker arm 302 has a blade pitch control link 304 secured to a first end thereof and a roller 308 secured to a second end opposite the pivot from the first end. In operation, roller 308 rides on a surface of a blade pitch control cam. The blade pitch control link 304 moves along with, but opposite to, the motion of roller 308 as it moves along the surface of the blade pitch control cam. FIGS. 7-11 depict detailed three-dimensional views of rocker arm 302, yoke 306 and blade pitch control link 304 in isolation.

It is believed that the operation and construction of the embodiments of the present patent application will be apparent from the Detailed Description set forth above. While the exemplary embodiments shown and described may have been characterized as being preferred, it should be readily understood that various changes and modifications could be made therein without departing from the scope of the present invention as set forth herein. 

1. A fluid turbine comprising: a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle; and a blade pitch control mechanism comprising a cam and at least one rocker assembly, each rocker assembly comprising a rocker arm operable to pivot about an axis of rotation, the blade pitch control mechanism being operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.
 2. The fluid turbine of claim 1, wherein the rocker assembly comprises a rocker cartridge which acts as a frame for the rocker assembly.
 3. The fluid turbine of claim 2, wherein the rocker cartridge has a cylindrical body protruding from the back of a front flange, and a generally-cylindrical aperture passing from front to back.
 4. The fluid turbine of claim 3, wherein a rocker arm is mounted to a shaft passing through the cylindrical aperture in the body of the rocker cartridge, and mounted in such a manner as to pivot about an axis of rotation passing through the aperture.
 5. The fluid turbine of claim 4, wherein a cam follower bearing is secured to the distal end of the rocker arm and oriented in such manner as to freely rotate about an axis of rotation generally parallel to, but offset from, the axis of rotation of the rocker arm.
 6. The fluid turbine of claim 1, further comprising a lever arm secured to an actuation rod in such a manner as to move an actuation rod as the rocker arm rotates.
 7. The fluid turbine of claim 6, wherein the actuation rod is secured at a first end to the rocker arm and at a second end to a rotor blade.
 8. A fluid turbine comprising: a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle; and a blade pitch control mechanism comprising a cam and at least one rocker assembly, each rocker assembly comprising a rocker arm operable to pivot about an axis of rotation and a cam follower bearing, secured to the distal end thereof, operable to ride on a surface of the cam, the blade pitch control mechanism being operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.
 9. The fluid turbine of claim 8, wherein the rocker assembly comprises a rocker cartridge which acts as a frame for the rocker assembly.
 10. The fluid turbine of claim 9, wherein the rocker cartridge has a cylindrical body protruding from the back of a front flange, and a generally-cylindrical aperture passing from front to back.
 11. The fluid turbine of claim 10, wherein the rocker arm is mounted to a shaft passing through the cylindrical aperture in the body of the rocker cartridge, and mounted in such a manner as to pivot about an axis of rotation passing through the aperture.
 12. The fluid turbine of claim 11, wherein a cam follower bearing is secured to the distal end of the rocker arm and oriented in such manner as to freely rotate about an axis of rotation generally parallel to, but offset from, the axis of rotation of the rocker arm.
 13. The fluid turbine of claim 8, further comprising a lever arm secured to an actuation rod in such a manner as to move an actuation rod as the rocker arm rotates.
 14. The fluid turbine of claim 13, wherein the actuation rod is secured at a first end to the rocker arm and at a second end to a rotor blade.
 15. A fluid turbine comprising: a frame, a rotor, comprising a hub secured to the frame in such manner as to rotate about an axis of rotation with respect thereto and at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle; and a blade pitch control mechanism comprising: a cam having a surface defining a rotor blade pitch profile and at least one rocker assembly, each rocker assembly comprising a rocker arm secured to the hub in such manner as to pivot about an axis of rotation with respect thereto and a cam follower bearing, secured to the distal end thereof, operable to ride on the surface of the cam, the blade pitch control mechanism being operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation.
 16. The fluid turbine of claim 15, wherein the rocker assembly comprises a rocker cartridge which acts as a frame for the rocker assembly.
 17. The fluid turbine of claim 16, wherein the rocker cartridge has a cylindrical body protruding from the back of a front flange, and a generally-cylindrical aperture passing from front to back.
 18. The fluid turbine of claim 17, wherein a rocker arm is mounted to a shaft passing through the cylindrical aperture in the body of the rocker cartridge, and mounted in such a manner as to pivot about an axis of rotation passing through the aperture.
 19. The fluid turbine of claim 15, wherein a cam follower bearing is secured to the distal end of the rocker arm and oriented in such manner as to freely rotate about an axis of rotation generally parallel to, but offset from, the axis of rotation of the rocker arm.
 20. The fluid turbine of claim 16, further comprising a lever arm secured to an actuation rod in such a manner as to move an actuation rod as the rocker arm rotates. 